Metal alloys, such as titanium alloys and steels, are known to have a good combination of mechanical properties for many structural applications, but these metal alloys do not meet the wear and corrosion resistance requirements for some structural applications, such as rotor blade applications, turbine blade applications, cutting tool applications, arc-heater applications, power generating surface applications, military hardware applications, sports industry equipment applications (e.g., golf club heads, shoe spikes, and snow skis), molten aluminum casting applications, and the like. Titanium alloys, for example, have many attractive properties, such as high specific strength and stiffness, relatively low density, and excellent corrosion resistance, but have poor resistance to wear and oxidation at high temperatures. Conventional surfacing (such as nitriding), coating deposition (such as plasma spraying and sputtering), and plating have significant shortcomings, which include potentially providing distorted substrates, deteriorated surfaces, and/or weak interfacial bonding. To overcome these shortcomings and provide high wear and corrosion resistant surfaces on metal alloy substrates, surface alloying and reactive surface modification have been developed—depositing and post-heat treating a unique combination of materials, selected based upon the substrate material and specific application environment. Functionally graded or layered interfaces are used to overcome interfacial bonding weaknesses, especially when the coefficient of thermal expansion (CTE) is significantly different between the substrate and a ceramic or cermet surface coating.
However, what are still needed in the art are hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications that overcome some of these attendant shortcomings.